Solvent, carbon loosener



iinite State SOLVENT, CARBON LOOSENER Charles F. Pickett, Bel Air,Robert E. Wagner, Jr., Havre de Grace, and Myer Rosenfeld, Baltimore,Md., assignors to the United States of America as represented by theSecretary of the Army No Drawing. Application November 23, 1956 7 SerialNo. 624,176

4 Claims. c1. 2s2-1ss (Granted under Title 35, US. Code (1952), see.266) The invention described herein may be manufactured and used by orfor the Government for governmental purposes without the payment to usof any royalties thereon.

This invention relates to the removal of carbon deposits from parts ofinternal combustion engines. More particularly the invention relates toa carbon-loosening solvent suitable for use in softening andfacilitating the effective removal of carbon, gum, oil, tar and othersurface contaminants, except rust and corrosion, from items such 2 aspistons, piston rings, carburetors, fuel pumps, and engine assemblies.

Various degrees of difficulty exist in the removal of socalied carbondeposits, depending on the particular conditions of operation of theengine, the nature of the lubricating oils, the nature of the fuel, andthe type of metal used in the manufacture of pistons. Variations in theresistance to removal of such carbon deposits are as wide as thevariations in the types of contaminants formed on the engine parts. Forexample, so-called light carbon deposits are readily removed where thechief active component of the carbon-loosening solvent is cresylic acid.Other types or" carbon deposits are more dilficult to remove, however,and require cleaning compositions which contain both cresylic acid andchlorinated solvents. Cresylic acid type compounds, however, areundesirable because of their toxicity, diificulty of disposal, and theirlimited supply which might well become critical at times of nationalemergency. Chlorinated compounds are also undesirable because of theirtoxic hazards. As a general rule, the smaller the molecule of thecleaning compound the faster its speed of cleaning. For example,methylene chloride has been found to be one of the most eifectivecleaning compositions when used as one of the principal activecomponents of carbon-loosening solvents. Methylene chloride has therelatively high M.A.C. value of 500 p.p.m., that is, for safetypurposes, the maximum allowable concentration of methylene chloridevapor in the air is approximately 500 parts per million. Whereconcentrations of methylene chloride exceed that figure, a definitetoxic hazard is presented. Since engine parts to be cleaned are eitherdipped directly intocontainers of solvent or the solvent is brushed onthe parts and allowed to stand for several hours before removal, theconcentration of solvent in the air merits serious consideration. Inspite of its relatively high M.A .C. value, however, methylene chlorideis undesirable for use as acarbon-loosening solvent since it has alowboiling point of 104 F. and its M.A.C. value is far exceeded at manyambient temperatures. For example, at 72 F. the concentration ofmethylene in the surrounding air would be in the neighborhood of 500,000p.p.m. For purposes of this invention, a nontoxic cleaner is defined asone which is usable at temperatures at which each of the ingredients hasa vapor concentration below the M.A.C. value for that ingredient.

Accordingly, the primary object of this invention is the formulation ofa cleaner having a cleaning ability equal to that of cleaners containinga combination of chlorinated hydrocarbons and cresylic type compoundsbut in 2329,78 Patented Mar. 22, 1%60 which chlorinated hydrocarbons ofthe naphthenic, aliphatic or aromatic types, as well as cresols,phenols, and their related compounds or their salts are absent.

A second object of this invention is the formulation of acarbon-loosening solvent having a desired degree of cleaning ability,but in which the vapor concentrations of hazardous components are keptbelow their maximum allowabie concentration values at the temperature ofuse.

The further object of this invention is the provision of compositionsfor removing carbon deposits which will remain stable and effective overa wide range of conditions.

Pursuant to the above mentioned objects of this invention, we have foundthat mixtures of monoethanol amine, water, and ethylene glycolmono-butyl ether provide the desired degree of cleaning ability even inthe absence of chlorinated hydrocarbons and phenolic or cresylic typecompounds. When this base is used, it has been found possible to adjustthe composition in such a manner that the vapor pressures of allcomponents lie below their M.A.C. (maximum allowable concentration)values even at temperatures as high as F. At a temperature of 130 F. thedesired degree of cleaning is generally obtained in approximately fourhours or less, which is considered adequate for all practical purposes.

It has also been found that additional improvement in cleaning may beobtained by the addition of small amounts of propylene glycol (0.5-l.2%by volume of total cleaner) or ethylene glycol (0.30.8% by volume ofcleaner) and by substituting ethylene glycol monoethyl ether in all orpart for the corresponding butyl ether, moi. for mol. The upperconcentration of this ethyl ether, however, must be limited if its vaporconcentration 'is to be maintained below its M.A.C. value at 130 F. Inremoving carbon deposits from engine parts, brushing with a bristlebrush is usually required subsequent to soaking in the cleanercomposition. Brushing is sometimes difiicult, however, if no soap ordetergent is present. Accordingly, it is advantageous to include somesoap or detergent in these cleaner compositions.

It has also been found that the same degree of cleaning may be obtainedby substituting, in part, aromatic hydrocarbons or mixtures of suchhydrocarbons for the ethylene glycol mono-butyl ether. Typicalcharacteristics of aromatics which have properties lying in the properrange of cleaning and which have vapor pressure characteristics enablingthem to be properly utilized for the purposes of the low toxicitycleaner of this invention are:

ASTM Method D86-52.

Other aromatic hydrocarbons may be used in cases where vaporconcentrations are not a factor. In order to prevent gelation which mayoccur on evaporation of volatile solvents, it may be desirable in somecases to add small amounts of a gelation inhibitor or phase stabilizer.In this respect either 3 methoxy butanol or hexylene glycol inconcentrations of from 1 to 5 percent by volume of the total cleaner hasbeen found to be eifective. Additionally it is frequently advisable toadd a corrosion inhibitor to the cleaner of this invention, particularlywhere metals such as zinc, copper, brass, lead, or aluminum are beingcleaned. Sodium silicate has been found to serve effectively as acorrosion inhibitor. Only small amounts of sodium silicate have beenfound to be necessary to prevent corrosion. Excess silicate settles tothe bottom of the mixture and the clear supernatant liquid may be useddirectly, or it may be filtered by means of ces-ass n v to any of theusual filter media such as paper mat and the like. 7

Although monoethanol amine is used in the preferred modification of thisinvention, other types of primary hy droxyamines may be used in itsplace. A primary hy- 4 of this invention are: Soap to 23%; aromatichydrocarbons 0 to 65%; ethylene glycol mono-butyl ether 7 to 64%; monoethanol amine 2 to 27%; water 3.5 to 57%; 3 methoxybutyl alcohol 1 to3%; propylene glycol 0.5 to 1.2%; ethylene glycol 0.3 to 0.8%. In molsper liter,

The ranges of percent by volume in which the components may be used ifincorporated in the cleaning composition and which are considered to bewithin the scope droxyamine is essential, however, to obtain propercleanethylene glycol moilo-butyl ether varies from .534 to 4.90 ing.Other types of amines, for example, diethanol and mono ethanol aminevaries from .335 to 4.52, amine, diethylethanol amine ,or tri'etllanolamine have While the instant invention has been shown and deyielded poorresults. scribed herein in what is conceived to be the most prac- Thelow vapor pressure of the hydroxyaniines is believed tical and preferredembodiment, it is recognized that dedue to the association of thehydroxy group of molepartures may be made therefrom within the scope ofthe cule with the amine group of another, through hydrogen invention,which is therefore not to be limited to the debonding. This associatedmolecule apparently breaks tails disclosed herein but is to be accordedthe full scope dOWIl readily give the Ifiactiofis Characteristic f an ofthe claims so as to embrace any and all equivalents. amine- Th8eificiency mono-631mm aminfi in C What is claimed and desired to besecured by United junction with the water and the ethylene glycol 11lono$1 1 Letters Patent is: butyl ether (alone or in part substituted byaromatic hy- W lai I drocarbons) may be due to the independent actionof 1. A non-toxic, carbon-loosening composition consistthe variouscleaner components on the components of lag entially, by volume, of from2 to 27 percent of the carbon deposits, with various degrees oflipophillc and a primary hydroxyamine selected from the groupconhydrophilic character. Too much of one component resisting ofmonocthanolamine and monopropanolamine, Suits in too little,l'eiativfiil, 0f the Oihfifs, 80 that of from 7 to 64 percent of anether selected from the boil components are not removed which wouldothergroup consisting of ethylene glycol monobutyl ether, wise expose itto soluble carbon components. Also, ethylene glycol monoethyl ether,propylene glycol monoditlerent particles of even the same soil molecule,micelle, butyl ether, ethylene glycol monopropyl ether and ethylorlarger particle may successively become solvated with one monophenylether, of from 3.5 to 57 percent Water the proper solvent. Insutiicientquantities could result and of from 0.3 to 1.2 percent of a polyhydricalcohol in the displacement of equilibria so that desolvation isselected from the group consisting of ethylene glycol and favored beforecomplete dispersion of the molecule, mipropylene glycol. celle, orlarger particle can occur. 2. A composition as "set forth in claim 1containing The following specific examples are given by way of 11- from1 to '5 percent by volume of a phase stabilizer lustrating the practiceof this invention. It should be unselected from the group consisting ofmethoxy butanol derstood, however, that monoproponol amine may be subandhexylene glycol. stituted mol. for mol. for the monoethanol amine in allthe 3. A composition as se't forth in claim 1 containing a illustrationsgiven below. Also, propylene glycol monosodium silicate corrosioninhibitor; outyl, or monoethyl or mono-isopropyl ether, ethylene gly- 4.A non toxic, carbon-loosening composition consistcol mono-propyl orisopropyl ether and ethylene glycol iiig essentially, by volume, of from2 to 27 percent monornono-phenyl ether may be substituted mol. for mol.for 'ethanolarnine, of from 7 to 64 percent ethylene glycol the ethyleneglycol monobutyl ether given in the below ilmonobu'tyl ether, of from3.5 to 57 percent water, of lustrations. Molecular volumes inmilliliters may be obfrom 0.5 to 1.2 percent propylene glycol, and offrom 1 tained for these substitutes by dividing the densities of to 5percent methoxybutanol.

Example No 1 2 a 4 s s 7 s 9 10 11 12 13 14 15 16 17 Soap 1e 1e 1e 1e ls16 15.8 23 10.5 Aromatics 45.6 45.3 8.5 41.4 64.8 13.1 34.1 39.0Ethylene Glycol Mono-Blltyl Ether. 30.4 30.2 10.5 27.6 7.2 64 23 13.821.9 25.4 19.4 11.9 12.0 9.5 0.6 12.6 12.0 Mono-EthanolAmine 5 a 25 2 s7 22 19.1 4.2 4.0 21.5 21.0 21.2 21.0 21.2 22.3 22.8 Viater a 3.5 10 1a7 13 24:38 16:8 19.6 53.7 52.0 52.5 52.0 52;! 55.1 513.4 PropyleneGlycol .76 1.1 1.1 1.1 3-MetlloXy-Bl1tylA ol 1.47 2.1 v

Sodium Silicate, 40 .12 0.1 0.3 0.5 0.3 0.5 Ethylene Glycol Mono-EthylEther 1.47 2.1 Ethylene Glycol Mono-PhenylEtller. 7 0 7 1 9.4 9.5Hexylene Glycol 4.8 4.8 4.8 4.8 Synthetic Detergent 1.9 1.9 1.0 1.9

these substances into their molecular weights. All vol- 55 ReferencesCited in the file of this patent umes are measured between F. and F. andall UNITED STATES AT values are in percent by volume unless otherwisespecifi- 11 34 Amthor at 7, 1936 Cally deslgnatefi; 2,089,212Kritchevsky Aug. 10, 1937 The compositions given m above Examples 3, 7,8 and 2,097,737 Pickett et a]. p Nov. 2' 1937 11-13 represent preferredembodiments of the invention 60 355 7 7 Bowman Aug 2 44 in view of thefact they possess the low M.A.C. values 2,3 3,114 p vi l Aug 21, 194.5desired in this type of composition. 2,466,632 B01115 Apr. 5, 1949 Incompositions using soap, where aromatic hydrocar- 2,509,197 Borus et a1.May 30, 1950 bons are used, it is desirable that the percentage of soap2,566,298 Irwin Sept.'4, 1951 be between 10 and 23 percent. In theabsence of aro- (55 "2,576,419 Sccfist Nov. 27, 1951 matic hydrocarbons,approximately 2 to 23 parts per volume of soap or synthetic detergentsare added tocom- I 4 OTHER R positions. Such additions much improve theease of Qi y F -j by Carbldeand Carbon brushing Chem. Corp.,' New York(1950).

7o Hexylene Glycol (Tech. Booklet SCzSO-l), pp. 8-1 2,

15, 191116 25, Pub. by ShellChel'n. Corp., New York (1950).

1. A NON-TOXIC, CARBON-LOOSENING COMPOSITION CONSISTING ESSENTIALLY BYVOLUME, OF FROM 2 TO 27 PERCENT OF A PRIMARY HYDROXYAMINE SELECTED FROMTHE GROUP CONSISTING OF MONOETHANOLAMINE AND MONOPROPANOLAMINE, OF FROM7 TO 64 PERCENT OF AN ETHER SELECTED FROM THE GROUP CONSISTING OFETHYLENE GLYCOL MONOBUTYL ETHER, ETHYLENE GLYCOL MONOETHYL ETHER,PROPYLENE GLYCOL MONOBUTYLE ETHER, ETHYLENE GLYCOL MONOPROPYL ETHER ANDETHYLENE MONOPHENYL ETHER, OF FROM 3.5 TO 57 PERCENT WATER AND OF FROM0.3 TO 1.2 PERCENT OF A POLYHDRIC ALCOHOL SELECTED FROM THE GROUPCONSISTING OF ETHYLENE GLYCOL AND PROPYLENE GLYCOL.